1. Field of the Invention
The present invention relates to a superconducting conductor employing an oxide superconducting material.
2. Description of the Background Art
In recent years, superconductors of ceramics, i.e., oxide superconductors, have been watched with interest as superconducting materials which exhibit higher critical temperatures. In particular, superconductors of yttrium, bismuth and thallium, which show high critical temperatures of about 90 K, 110 K and 120 K respectively, are expected as practicable materials. A wire of such an oxide superconductor, which is covered with a metal sheath, is particularly suitable for long wire fabrication. Thus, study has been made as to application of such an oxide superconductor to a cable, a bus bar, a current lead, a magnet and the like.
However, it is difficult to independently apply such a high-temperature superconducting material to a cable, a current lead or the like, since there is some problem regarding strength.
Further the superconducting material must withstand a temperature cycles between the working temperature and the room temperature. Superconducting properties, particularly the critical current density, of a conventional superconducting conductor have problem reduced due to such a temperature change.